Liquid antimony pentafluoride

In order to establish the identity of the trimethylcarbonium ion, the t-butyl fluoride-antimony pentafluoride system was investigated. It was found that when the vapour of t-butyl fluoride was passed over the surface of purifled liquid antimony pentafluoride (with exclusion of moisture and oxygen) a stable complex layer is formed on the top of the antimony pentafluoride. When this layer was separated and its proton magnetic resonance investigated (see subsequent discussion) the spectrum was found to be identical with that of the least-shielded species formed by decarbonylation of the t-butyloxocarbonium salt... 

The main use of this definition is for solvents that are capable of forming both anions and cations by autolysis. There are other examples, such as liquid antimony pentafluoride, that do not depend upon the transfer of a proton to effect the ionisation of the solvent. Suggest the autolytic reaction for this solvent. 

Liquid antimony pentafluoride has been used as a solvent to study the properties of carbonium ions, because such ions are relatively stable in this solvent. 

Consider, however, a solution of Xep2 in an excess of the strong fluoride ion acceptor, liquid antimony pentafluoride, SbF5. The Xep2 donates a fluoride to the solvent, and forms XeF+(apf), where apf denotes SbFs- If xenon gas is now brought into contact with the solution at 2-3 atmospheres pressure, a green solution of the paramagnetic ion Xc2+ is formed ... 

Properties. Antimony pentafluoride [7783-70-2], SbF, is a colorless, hygroscopic, very viscous liquid that fumes ia air. Its viscosity at 20°C is 460 mPa-s(=cP) which is very close to the value for glycerol. The polymerization of high purity SbF at ambient temperature can be prevented by addition of 1% anhydrous hydrogen fluoride, which can be removed by distillation prior to the use of SbF. The pure product melts at 7°C (11), boils at 142.7°C,... 

It was indeed found necessary to have excess antimony pentafluoride present in order to obtain stable alkylcarbonium hexafluoroantimonate complexes. Antimony pentafluoride is a liquid Lewis acid fluoride (b.p. 148-150°) of low dielectric constant (e 3), which has been shown by fluorine N.M.R. studies in the pure liquid state and in solution to exist in both cyclic and acyclic polymeric forms involving fluorine bridges. The antimony is in approximately octahedral co-ordination with predominant bridging by coordinating fluorines (Gillespie and Rothenbury, 1963). As fluorine generally does not show bridging properties, the structure of antimony pentafluoride itself indicates the very... 

Antimony pentafluoride (4.94 g, 22.8 mmole) is added, in a good dry box, to side B of the reaction flask using an all-glass syringe. Elemental mercury (2.74 g, 13.7 mmole) is added to side A. The reaction vessel is fitted at E and F with Nupro or similar metal valves, removed from the dry box, and attached to a vacuum line that has been thoroughly flamed before use. Approximately 10 mL of sulfur dioxide is transferred to side B by cooling with liquid N2, and the... 

The order of decreasing Lewis basicity toward trimethylaluminum is thiane, thiolane, diethyl (or dimethyl) sulfide, thietane and 2-methylthiirane (67IC1461). Thietane can be protonated at -60 °C with fluorosulfonic acid in antimony pentafluoride-liquid sulfur dioxide the NMR spectrum shows bands at 8 7.40 (S—H) and 3.20-4.40 p.p.m. (C—H) (71JOC1121). 

Lewis Acid Complexes. Sulfolane complexes with Lewis acids, such as boron trifluoride or phosphorus pentafluoride (17). For example, at room temperature, sulfolane and boron trifluoride combine in a 1 1 mole ratio with the evolution of heat to give a white, hygroscopic solid which melts at 37°C. The reaction of sulfolane with methyl fluoride and antimony pentafluoride in liquid sulfur dioxide gives crystalline tetrahydro-l-methoxythiophenium-1-oxidehexafluoroantimonate, the first example of an alkoxysulfoxonium salt (18). 

Arsenic Pentafluoride, AsFs, may be prepared by the interaction of arsenic and fluorine in a platinum vessel,2 or by the action of bromine and antimony pentafluoride on arsenic trifluoride.3 The reagents should be dry, and if the reaction in the second case is carried out in a glass vessel, the apparatus should be in one piece and well dried. The bromine is added to the mixture of fluorides at - 20° C. and, after cooling in liquid air, the arsenic pentafluoride is obtained by heating on a water-bath at 55° C., the gas passing through a reflux condenser to a receiver surrounded by liquid air. The product contains bromine, which is removed by passing the gas over molten sulphur. 

Antimony Pentafluoride. Antimony pentafluoride (SbF5) is a highly associated, colorless, very viscous liquid at room temperature. It is hygroscopic and fumes in moist air. Its viscosity at 20°C is 460 cP, which is close to that of glycerol. The pure liquid can be handled and distilled in glass if moisture is excluded. Commercial antimony pentafluoride is shipped in steel cylinders or in perfluoroethylene bottles for laboratory quantities. 

Pure crystalline I2+Sb2F11 has been prepared by the reaction of iodine with antimony pentafluoride in liquid sulfur dioxide as solvent.789 After removal of insoluble SbF3, deep blue crystals of l2+Sb2Fn were obtained from the solution. An X-ray crystallographic structure determination showed the presence of the discrete... 

Antimony pentafluoride is a colorless, very viscous, fuming liquid. Its viscosity is 460 mpa which is very close to the value of glycerol. The polymerization of SbF5 can be... 

Antimony pentafluoride, SbFs, is a colorless, very viscous liquid (mp 8.3 °C, bp 141 °C) formed by reaction of HF with... 

The blue solid prepared by Rulf et al. (9) in 1906 and thought to be (SbF5)aI was probably a mixture of an la fluoroantimonate salt, and some Sb(III)-containing material. Pure crystalline la SbaFu has recently been prepared by the reaction of iodine with antimony pentafluoride in liquid sulfur dioxide as solvent (11). After removal of insoluble SbFg, deep blue crystals of la SbaFi were obtained from the solution. An X-ray crystallographic structure determination showed the presence of the discrete ions la and SbaFu . Crystalline solids that can be formulated as la SbaFu and Ia TaaFii have also been prepared by Kemmitt et al. (4) by the reaction of iodine with antimony or tantalum pentafluorides in iodine pentafluoride solutions. 

Antimony Pentafluoride. Antimony(V) fluoride [7783-70-2], SbF5, is a colodess, hygroscopic, viscous liquid that has SbF units with cis-fluorines bridging to form polymeric units. 19F nmr shows that at low temperatures there are three different types of F atoms (28). Contamination with a small amount of HF markedly decreases the extent of polymerization. The vapor density at 150 °C corresponds to the trimer. The solid is a cis- flu o tine - b ridge d tetramer (29). 

Arsenic pentafluoride (arsenic(V) fluoride), AsF5, is a colorless gas that condenses to a yellow liquid its dielectric constant is 12.8 at 20 °C. It is formed by reaction of a mixture of bromine and antimony pentafluoride with arsenic trifluoride. The molecule is a trigonal bipyramid and is somewhat dissociated as indicated by vapor density measurements. 

The preparation and properties of homopolyatomic cations of the Group VI elements have been reviewed recently.1 The general method described below, involving the oxidation of elemental sulfur, selenium, and tellurium with either antimony pentafluoride or arsenic pentafluoride in liquid sulfur dioxide, is convenient for the preparation of compounds containing these polyatomic cations. The procedure is basically that briefly described previously2 for the preparation of Se8(Sb2F j i )2. 

Arsenic pentafluoride (2.08 g., 0.012 mole) is condensed onto powdered sulfur (1.047 g., 0.033 mole) and frozen sulfur dioxide at — 196°, and the reaction vessel is heat-sealed at C and D. The mixture is allowed to warm to room temperature. The solution immediately develops a red color owing to (S16)2 +, just as in the case of the antimony pentafluoride reaction, but on stirring for 1 hour a blue solution is obtained. The reaction is complete within 3 hours. The S02-soluble S8(AsF6)2 is extracted until the solution in A is colorless and there is no residue (five extractions are normally sufficient). As described in the general procedure, flask B is heat-sealed at F while keeping A at liquid N2 temperature. The powdered product obtained from B is further dried to give a yield of 90 % or better. In the typical experiment described 2.48 g. (0.0039 mole) was obtained a 96% yield based on sulfur. Anal. Calcd. for S8As2F12 S, 40.43 As, 23.62 F, 35.94. Found S, 40.53 As, 23.63 F, 36.12. 

A mixture of 2.81 g. (22 mmoles) of tellurium and 10.25 g. (47 mmoles) of antimony pentafluoride in liquid sulfur dioxide is stirred for 3 days at — 23°. The solution develops a red color after about 2 hours of stirring at — 23°. The solution is filtered to leave a yellow residue, which is repeatedly washed with sulfur dioxide until the washings are colorless and all the red compound has been removed. In this particular reaction, since both red and yellow products are needed, flask B is not heat-sealed but is closed with a Nupro Teflon valve. After all the S02 has been removed under vacuum, flask B is heat-sealed at F. The yellow product is discussed below. The product obtained from flask B is a semicrystalline red material the yield is 6.0 g. (4.2 mmoles) 75% yield based on tellurium. Anal. Calcd. for Te4Sb4F22 Te, 35.97 Sb, 34.45 F, 29.60. Found Te, 35.88 Sb, 34.23 F, 32.21. 

Antimony pentafluoride (mp 280 K, bp 422 K) is prepared from Sbp3 and F2, or by reaction 14.85. In the solid state, Sbp5 is tetrameric (Figure 14.12a) and the presence of Sb—F—Sb bridges accounts for the very high viscosity of the liquid. Antimony pentachloride (mp 276 K, bp 352K)... 

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